#13998: hash of a pickled Sequence is broken
----------------------------+-----------------------------------------------
Reporter: slabbe | Owner: slabbe
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.7
Component: pickling | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
----------------------------+-----------------------------------------------
Description changed by slabbe:
Old description:
> The following works::
>
> {{{
> sage: M = ModularSymbols(1,12,sign=1)
> sage: M
> Modular Symbols space of dimension 2 for Gamma_0(1) of weight 12 with
> sign 1 over Rational Field
> sage: S =
> M.cuspidal_submodule().decomposition()[0].free_module().basis()
> sage: type(S)
> <class 'sage.structure.sequence.Sequence_generic'>
> sage: S
> [
> (1, 0)
> ]
> sage: hash(S)
> 979268961
> }}}
>
> But if you do the same from a certain pickled object, it is broken
> (tested on sage-4.7 and sage-5.6.rc0)::
>
> {{{
> sage: M =
> load('http://sage.math.washington.edu/home/slabbe/LMFDB/mstest.sobj')
> Attempting to load remote file:
> http://sage.math.washington.edu/home/slabbe/LMFDB/mstest.sobj
> Loading: [.]
> sage: M
> Modular Symbols space of dimension 2 for Gamma_0(1) of weight 12 with
> sign 1 over Rational Field
> sage: S =
> M.cuspidal_submodule().decomposition()[0].free_module().basis()
> sage: type(S)
> <class 'sage.structure.sequence.Sequence_generic'>
> sage: S
> [
> (1, 0)
> ]
> sage: hash(S)
> Traceback (most recent call last)
> ...
> AttributeError: 'Sequence_generic' object has no attribute
> '_Sequence_generic__hash'
> }}}
>
> This particular problem was reported by LMFDB developper who understands
> that Sage do not guarrenty that pickled object are supported by later
> version of Sage.
New description:
The following works::
{{{
sage: M = ModularSymbols(1,12,sign=1)
sage: M
Modular Symbols space of dimension 2 for Gamma_0(1) of weight 12 with
sign 1 over Rational Field
sage: S =
M.cuspidal_submodule().decomposition()[0].free_module().basis()
sage: type(S)
<class 'sage.structure.sequence.Sequence_generic'>
sage: S
[
(1, 0)
]
sage: hash(S)
979268961
}}}
But if you do the same from a certain pickled object, it is broken (tested
on sage-4.7 and sage-5.6.rc0)::
{{{
sage: M =
load('http://sage.math.washington.edu/home/slabbe/LMFDB/mstest.sobj')
Attempting to load remote file:
http://sage.math.washington.edu/home/slabbe/LMFDB/mstest.sobj
Loading: [.]
sage: M
Modular Symbols space of dimension 2 for Gamma_0(1) of weight 12 with
sign 1 over Rational Field
sage: S =
M.cuspidal_submodule().decomposition()[0].free_module().basis()
sage: type(S)
<class 'sage.structure.sequence.Sequence_generic'>
sage: S
[
(1, 0)
]
sage: hash(S)
Traceback (most recent call last)
...
AttributeError: 'Sequence_generic' object has no attribute
'_Sequence_generic__hash'
}}}
This particular problem was reported by LMFDB developper who understands
that Sage do not guarrenty that pickled object are supported by later
version of Sage. Let's fix this problem !!!
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13998#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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